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Topic: What on earth am I doing wrong - redox oxidation states  (Read 1249 times)

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Offline Hentrox

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What on earth am I doing wrong - redox oxidation states
« on: January 19, 2023, 03:48:52 AM »
Question c. (shown in photo 1). Book states that answer is " Cu oxidised (0  :rarrow: +2), N reduced (+5  :rarrow: +4)"

As can be seen from my working on it in photo 2, I have also come to this conclusion, however, it also appears that H has gone from an oxidation state of +1  :rarrow: +2, and that O has gone from an oxidation state of -6  :rarrow: -4 (i.e. they've both been oxidised). Why am I wrong? I have followed everything the teacher has said to do...

And then in question d. it gets even more mind f**king. You can see my assigning of oxidation states/numbers to the elements in the bottom of photo 2. I get that Pb has gone from +4 to +2 and that Cl has gone from -1 to 0 (in one situation...). Cl HAS ALSO gone from -1 to -2??? WHAT??? On top of that, like in the previous question, H has gone from +1 to +2. I am losing my mind.

Offline Hunter2

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Re: What on earth am I doing wrong - redox oxidation states
« Reply #1 on: January 19, 2023, 04:40:36 AM »
Hydrogen and oxygen dont change its oxidation numbers in these reactions.
« Last Edit: January 19, 2023, 03:09:27 PM by Borek »

Offline Corribus

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Re: What on earth am I doing wrong - redox oxidation states
« Reply #2 on: January 19, 2023, 11:50:04 AM »
@Hentrox, you seem to be forgetting that some of those compounds have multiple oxygen atoms. The oxidation state of oxygen in nitric acid is not -6. It is -2 per oxygen atom. And in nitrogen dioxide the oxygen state of oxygen is still -2 per oxygen atom. But there are only two oxygen atoms in nitrogen oxide, so the overall contribution of charge from oxygen atoms in this compound is -4. This does not mean that oxygen has changed oxidation states. Oxygen atoms have a -2 oxidation state in both compounds.
What men are poets who can speak of Jupiter if he were like a man, but if he is an immense spinning sphere of methane and ammonia must be silent?  - Richard P. Feynman

Offline Hentrox

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Re: What on earth am I doing wrong - redox oxidation states
« Reply #3 on: January 19, 2023, 04:10:48 PM »
Thanks so much for the answers guys! Helped tremendously!

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